HELL CREEK FORMATION, MONTANA

With its three-horned head, the triceratops is one of the most famous species of dinosaur. They lived at the very end of the Cretaceous Period before the fatal mass-extinction triggered by the asteroid that caused the Chicxulub crater 65 million years ago. These 30-foot long herbivores, weighing 12 tonnes, roamed in an area that is now to the East of the Rocky Mountains in North America, which then had a mild climate. They lived contemporaneously with, and were preyed upon by, Tyrannoraurs rex.